1. Field of the Invention
The present invention relates to a pen-type input device and electronic information board system.
2. Description of the Related Art
In recent years, electronic information boards such as a so-called electronic blackboard or a so-called interactive whiteboard (IWB) have been developed. For example, as disclosed in Patent Document 1, one type of the electronic information board includes an image display device having a large screen (the diagonal dimension is, for example, 40 inches to 60 inches) using a flat panel such as a liquid crystal panel or a plasma panel, a coordinate detection device (a touch panel) which detects the coordinate of a position where a display face is touched, and a control device which causes various images (images containing a character, a number, or a figure) written on the display face of the image display device to be displayed based on coordinate data output from the coordinate detection device.
Further, it is possible to enlarge and display an image displayed by a display of a personal computer by connecting the electronic information board with a personal computer. This electronic information board can be used for presentation in a meeting.
Further, the system of this electronic information board has a function of superposing a graphic of a handwritten character written by a pen-type input device (an object to be detected) on an image displayed on a display face by causing the pen-type input device to touch a touch panel and a function of taking a screen of a personal computer into and superposing and drawing graphics written by the pen-type input device on the screen.
For example, Patent Document 2 discloses a pen-type input device including a writing unit which transmits a transcription detecting signal by detecting a transcribing operation when a penpoint made of, for example, an elastic member is moved while the penpoint touches a touch panel.
In a case where the pen-type input device is used to write on an electronic information board, the pen-type input device is moved so as to go along a display surface of the electronic information board while the penpoint touches the display surface of the electronic information board, and therefore the coordinate of the position where the penpoint touches the display surface is detected by an optical sensor and characters and graphic symbols can be written like an ordinary blackboard or whiteboards. Further, the penpoint is made of a material having elasticity and the front end recess of the pen-type input device includes a detection switch for detecting a displacement caused by pressure received by the penpoint from the contacting display unit in order to improve a write feeling at a time of a contact of the penpoint with the display face of the electronic information board. Then, the electronic information board displays the characters and the graphic symbols which are written on the display face based on information of the contact position of the pen-type input device which touches the display face and a signal transmitted from the detection switch of the pen-type input device.
Patent Document 1: Japanese Patent No. 4627781
Patent Document 2: Japanese National Publication of International Patent Application No. 2002-509308
At a time of the transcribing operation using the above pen-type input device, a contact pressure (a compression load) is applied onto the penpoint against the display face. Therefore, the penpoint is compressed by pressure in an axial direction so that an outer peripheral side of the penpoint expands in a radius direction. After repeated applications of the contact pressure onto the penpoint, the shape of the penpoint gradually deforms and finally the outer peripheral side of the penpoint may not return from the expanded state. After the penpoint is deformed onto the outer peripheral side as described above, the deformed part of the penpoint contacts the inner wall of the front end recess of the pen-type input device. Then, a write switch cannot be normally operated. Thus, there occurs a problem that a writing operation using the pen-type input device cannot be recognized.